Camera apparatus

ABSTRACT

A camera apparatus includes: an image pickup device; a lens configured to converge light from an object to the image pickup device; a coaxial circular-shaped lens cover in which the lens is arranged; a plurality of infrared light sources arranged to surround the lens in the lens cover; and a light shielding member which is provided between the lens and the infrared light source and which has an opening. The opening is outwardly extended at corner optical path portions which correspond to diagonal corners of an angle of view of the image pickup device.

BACKGROUND

1. Technical Field

The present invention relates to a camera apparatus including a lightshielding member provided at a lens cover.

2. Background Art

Some of surveillance cameras use infrared light having permeability orspectral characteristics superior to visible light. In the type of thesurveillance camera, in order to prevent the infrared light of aninfrared light source arranged around a lens from being incident on anoptical system directly, a light shielding member is provided at a lenscover. JP-B-3988051 discloses an imaging apparatus, which is an exampleof a technique to provide a light shielding plate on a lens hood.

FIGS. 9A and 9B shows the surveillance camera of the related art whichshields infrared light with a light shielding member. The surveillancecamera includes an image pickup device 101, a lens 102 which convergeslight from an object to the image pickup device 101, and a circularcoaxial lens cover 103 which has the lens 102 inside thereof. In thelens cover 103, a plurality of infrared light sources 104 are annularlyarranged to surround the lens 102. A planar or cylindrical lightshielding member 105 having a circular opening shape is provided betweenthe lens 102 and the infrared light source 104. Since the lightshielding member 105 is provided, the infrared light can be suppressedto incident on the lens 102 without passing through the object from theinfrared light source 104.

SUMMARY

However, when the light shielding member 105 is circular shape, avignetting occurs in a diagonal direction of an angle of view. In a caseof the light shielding member 105 having a circular shape, a horizontalangle of view is limited to about 80 degree to obtain an image withoutthe vignetting. Accordingly, in a case where the light shielding member105 is the circular shape, in order to obtain wider angle of view of thelens, it is necessary to increase the diameter of the light shieldingmember 105. As a result, the whole of the light shielding member 105becomes large in the diameter, and the cross section of a productbecomes large.

The present invention was made in view of the above-describedcircumstances, and an object thereof is to provide a camera apparatuscapable of obtaining the wide angle image without increasing the size ofthe apparatus.

An aspect of the invention provides a camera apparatus including: animage pickup device; a lens configured to converge light from an objectto the image pickup device; a coaxial circular-shaped lens cover inwhich the lens is arranged; a plurality of infrared light sourcesarranged to surround the lens in the lens cover; and a light shieldingmember which is provided between the lens and the infrared light sourceand which has an opening, wherein the opening is outwardly extended atcorner optical path portions which correspond to diagonal corners of anangle of view of the image pickup device.

According to the camera apparatus of the aspect, the product can bedecreased in size while obtaining the wide angle image withoutvignetting.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a surveillance camera of an embodimentaccording to the invention;

FIG. 2 is an exploded perspective view of the surveillance cameraillustrated in FIG. 1;

FIG. 3A is a cross-sectional view of a lens cover portion including anoptical axis thereof illustrated in FIG. 2, and FIG. 3B is a front viewthereof;

FIG. 4A is a perspective view of the lens cover with cutaway a portionthereof, and FIG. 4B is a front view of a cutaway surface thereof;

FIG. 5A is a front view of a light shielding member having an openingshape in a triangular bulging-shaped portion, FIG. 5B is a front view ofa light shielding member having an opening shape similar to a light fluxcorresponding to an angle of view, FIG. 5C is a front view of a lightshielding member having an opening shape of a rectangular shape, andFIG. 5D is a front view of a light shielding member having an openingshape in a half oval-shaped portion;

FIG. 6A is a perspective view in the vicinity of a lens representing anoptical path corresponding to the angle of view, FIG. 6B is aperspective view in the vicinity of a lens including a light shieldingmember of an embodiment, and FIG. 6C is a perspective view in thevicinity of a lens including a light shielding member of a comparativeexample;

FIG. 7A is a front view of FIG. 6C, and FIG. 7B is a front view of animage obtained by the light shielding member;

FIG. 8A is a front view of FIG. 6B, and FIG. 8B is a front view of animage obtained by the light shielding member; and

FIG. 9A is a cross-sectional view of a lens cover portion of the relatedart including an optical axis thereof, and FIG. 9B is a front viewthereof.

DETAILED DESCRIPTION

Hereinafter, embodiments of the invention are described with referenceto drawings.

FIG. 1 is a perspective view of a surveillance camera which serves as acamera apparatus of an embodiment according to the invention.

A surveillance camera 11 of the embodiment is covered by a cover case 15including a front cover 12, a main body cover 13 and a rear cover 14.The cover case 15 is further covered by a top plate 16 at an upperportion thereof. In the surveillance camera 11, a mounting seat 17 isprovided at the location of the main body cover 13, and the mountingseat 17 is fixed at a support which meets a CD including a female LANterminal (not shown).

FIG. 2 is an exploded perspective view of the surveillance camera 11illustrated in FIG. 1.

In the main body cover 13, a seal frame material 18, a heat sink 19, arear surface pressing plate 20 and an operation portion cover 21 areaccommodated. In the operation portion cover 21, an image pickup device22 is accommodated. In the image pickup device 22, a cylindrical lensseat 23 is provided, and the lens seat 23 accommodates therein a lens24. The lens 24 converges light from the object to the image pickupdevice 22.

At an outer periphery of the lens seat 23, an annular light sourcemounting board 25 is inserted from outside. At the light source mountingboard 25, an annular infrared light source 26 is mounted. In theembodiment, the infrared light source 26 includes an annular LED lightemitting portion 28 in which a plurality of LEDs 27 are arranged in acircumferential direction. As the infrared light source 26, a lightsource other than the LED may be used.

The outside of the annular LED light emitting portion 28 is covered by alens cover 29. The lens cover 29 is accommodated in the front cover 12.The lens cover 29 is formed in a coaxial circular shape and includestherein the annular LED light emitting portion 28 and the lens 24. Inother words, the infrared light source 26 surrounds the lens 24 at theinside of the lens cover 29 and is annularly arranged. A light shieldingmember 30 is provided between the lens 24 and the annular LED lightemitting portion 28.

FIG. 3A is a cross-sectional view of a lens cover portion illustrated inFIG. 2 including an optical axis thereof, FIG. 3B is a front viewthereof, FIG. 4A is a perspective view of the lens cover 29 with cutawaya portion thereof and FIG. 4B is a front view of a cutaway surfacethereof.

As shown in FIG. 4A, the light shielding member 30 is coaxially mountedto a circular end plate 31 which closes one axial end of the lens cover29. The circular end plate 31 of the lens cover 29 is formed by a memberwhich transmits at least the infrared light. As shown in FIG. 4B, at thecircular end plate 31, a light shielding member mounting hole 32, inwhich the light shielding member 30 penetrates and is assembled, isformed. The light shielding member 30 is inserted into the lightshielding member mounting hole 32. A rear end of the light shieldingmember 30, which is mounted in the light shielding member mounting hole32, is fitted and fixed in a concave portion 33 of the light sourcemounting board 25. In other words, a front end of the light shieldingmember 30 is fixed in the light shielding member mounting hole 32, andthe rear end thereof is fixed to the light source mounting board 25. Thelens 24 fixed at the lens seat 23 is arranged an inside of the lightshielding member 30. In addition, a front opening portion 34 of thelight shielding member 30 is covered by a cover member 35 whichtransmits at least the infrared light. The cover member 35 is separatedfrom the circular end plate 31.

FIG. 5A is a front view of a light shielding member 30 having an openingshape in a triangular bulging-shaped portion 36, FIG. 5B is a front viewof a light shielding member 42 having an opening shape similar to alight flux 37 (see FIG. 6A, FIG. 6B and FIG. 6C) corresponding to anangle of view, FIG. 5C is a front view of a light shielding member 44having an opening shape of a rectangular shape and FIG. 5D is a frontview of a light shielding member 45 having an opening shape in a halfoval-shaped portion 38.

The light shielding member 30 has an opening shape which outwardlyextends at a diagonal corner corresponding optical path portion 39(hereinafter referred to as a corner optical path portion 39)corresponding to the diagonal corners of the angle of view in the imagepickup device 22. In the embodiment, as shown in FIG. 5A, the lightshielding member 30 is configured such that the opening shape thereofhas the triangular bulging-shaped portion 36 which outwardly protrudesfrom a circular opening shape portion 40 at a position corresponding tothe corner optical path portion 39. Accordingly, in the embodiment,while the circular opening shape portion 40 of the light shieldingmember 30 is not changed from a shape of the related art, only thetriangular bulging-shaped portion 36 protruding from the circularopening shape portion 40 is formed to avoid the corner optical pathportion 39 which protrudes outwardly. With this configuration, it is notnecessary to largely change the location of the infrared light source 26from the related art.

Next, the function of the surveillance camera 11 having theconfiguration described above is described while comparing with acomparative example.

FIG. 6A is a perspective view in the vicinity of a lens representing anoptical path corresponding to the angle of view, FIG. 6B is aperspective view in the vicinity of a lens including a light shieldingmember 30 of an embodiment, FIG. 6C is a perspective view in thevicinity of a lens including a light shielding member 105 of acomparative example, FIG. 7A is a front view of FIG. 6C, FIG. 7B is afront view of an image obtained by the light shielding member, FIG. 8Ais a front view of FIG. 6B, FIG. 8B is a front view of an image obtainedby the light shielding member.

As shown in FIG. 6A, in a case where the light passing through the lens24 produces an image of a rectangular shape, for example, on a CCD (or aCMOS) of the image pickup device 22, the light flux 37 before enteringinto the lens 24 has a cross-sectional shape surrounded by light fluxlines 41 such that the corner optical path portion 39 tends to protrude(the corner extends radially). Specifically, in a case of a lens 24 of awide-angle lens system, the light hits obliquely on a peripheral portionof the CCD. When the light obliquely enters the CCD, electric chargecannot be generated sufficiently. The diagonal corner portion has atendency to protrude in order to compensate for this of the lightamount.

Here, for example, as shown in FIG. 6C, when using the light shieldingmember 105 of the circular shape according to the comparative examplesimilar to the related art, as shown in FIG. 7A, the corner optical pathportion 39 protruding outward is positioned the outside of the lightshielding member 105 and is vignetted. As a result, as shown in FIG. 7B,the image becomes dark at the diagonal corner portion.

In contrast, in the configuration using the light shielding member 30according to the embodiment shown in FIG. 6B, as shown in FIG. 8A, thetriangular bulging-shaped portion 36 outwardly protruding from thecircular opening shape portion 40 is provided at a positioncorresponding to the corner optical path portion 39. Accordingly, theoptical path for the diagonal corner is secured, which is necessary atthe time of wide angle of the lens. The lens optical path and an imagepickup range generally tend to protrude in the diagonal corner portion.With this configuration, as shown in FIG. 8B, the image with novignetting can be obtained without increasing the diameter of the lightshielding member 30 as a whole, by outwardly extending only the opticalpath portion 39 in the light shielding member 30.

Next, a modification of the light shielding member 30 is described.

As shown in FIG. 5B, the opening of the light shielding member 42 mayhave a shape similar to a cross sectional shape of the light flux 37 ona plane 43 (see FIG. 6A) orthogonal to a center axis of the light flux37 which corresponds to the angle of view in the image pickup device 22and which enters from the object into the lens 24.

According to the light shielding member 42 of the modification, theshape thereof is somewhat complicated. However, the light shieldingmember 42 can be formed in a minimum size without occurrence of thevignetting.

As shown in FIG. 5C, the opening of the light shielding member 44 may bea rectangular shape which is defined by straight lines which connect theprotruding ends of the adjacent corner optical path portions 39.

According to the light shielding member 44 of the modification, thelight shielding member 44 can be produced in the rectangular shape whichis easily manufactured without the vignetting. Even in the case, thelight shielding member 44 can be formed smaller than the case where thelight shielding member 105 of the circular shape of the related art as awhole is increased in the diameter, since when the diameter of the lightshielding member 105 is increased, the diameter of the opening becomes adiameter of a circumscribing circle of the rectangular shape of thelight shielding member 44.

As shown in FIG. 5D, the opening of the light shielding member 45 mayhave the half oval-shaped portion 38 which outwardly bulges from thecircular opening shape portion 40 at the position corresponding to theoptical path portion 39.

According to the light shielding member 45 of the modification, whilethe circular opening shape portion 40 of the light shielding member 30is not changed from a shape of the related art, the half oval-shapedportion 38 protrudes radially from the circular opening shape portion40. Accordingly, it is not necessary to largely change the location ofthe infrared light source 26 from the related art. In addition,according to the configuration, the manufacture becomes easy.Furthermore, by changing the protrusion length of the half oval-shapedportion 38, the light shielding member can easily deal with the opticalpath portion 39 where the degree of the protrusion increases anddecreases according to the degree of the wide angle.

According to the surveillance camera 11 of the embodiment, the productcan be decreased in size while obtaining the wide angle image withoutvignetting.

The embodiment may be applied to the camera apparatus corresponding tothe wide angle image without enlarging the cross section of the product.

This application claims the benefit of Japanese Patent Application No.2011-170759 filed on Aug. 4, 2011, the contents of which areincorporated herein by reference.

What is claimed is:
 1. A camera apparatus comprising: an image pickup device; a lens configured to converge light from an object to the image pickup device; a circular-shaped lens cover, the lens cover being coaxially positioned about the lens; a plurality of infrared light sources arranged to surround the lens in the lens cover; and a light shielding member which is provided between the lens and the infrared light sources and which has an opening, wherein the opening extends outwardly at corner optical path portions which correspond to diagonal corners of an angle of view of the image pickup device, the opening of the light shielding member having a periphery comprising a plurality of first arcuate portions and a plurality of second portions having a shape different than a shape of the first arcuate portions, each of the second portions being provided between two of the first arcuate portions, the second portions corresponding to the corner optical path portions and including at least one non-arcuate portion.
 2. The camera apparatus according to claim 1, wherein the opening of the light shielding member has triangular bulging-shaped portions which outwardly protrude from a circular opening shape and which are provided at positions corresponding to the corner optical path portions, the triangular bulging-shaped portions comprising the second portions.
 3. The camera apparatus according to claim 1, wherein the opening of the light shielding member has a circular opening shape with half oval-shaped portions which outwardly bulge from a circular opening shape portion at positions corresponding to the corner optical path portions, the half oval shaped portions comprising the second portions.
 4. The camera apparatus according to claim 1, wherein an outer periphery of the lens is circular.
 5. The camera apparatus according to claim 1, further comprising a circular end plate provided at a distal end of the lens cover, the circular end plate comprising a light shielding member mounting hole configured to receive an end of the light shielding member, the light shielding member mounting hole extending through a thickness of the circular end plate.
 6. The camera apparatus according to claim 5, a frontmost end of the light shielding member is secured within the light shielding member mounting hole and a rearmost end of the light shielding member is secured to a light source mounting board on which the plurality of infrared light sources are mounted.
 7. The camera apparatus according to claim 5, a frontmost end of the light shielding member is covered by an infrared light transmissive cover member.
 8. The camera apparatus according to claim 1, further comprising a circular end plate provided at a distal end of the lens cover, a frontmost end of the light shielding member is covered by an infrared light transmissive cover member, the infrared light transmissive cover member being separate from the circular end plate.
 9. The camera apparatus according to claim 1, the second portions including two non-arcuate shaped portions.
 10. The camera apparatus according to claim 1, a junction between each of the first arcuate portions and an adjacent second portion defining a point of discontinuity in the shape of the periphery of the light shielding member.
 11. The camera apparatus according to claim 1, the light shielding member having a proximal end closest to the lens and a distal end distant from the lens, the surface of the light shielding member between the proximal and distal ends being parallel to an optical axis of the lens. 